1. Field of the Invention
The present invention generally pertains to an apparatus and method for setting blind rivet type fasteners or the like. More particularly, it is directed to a novel and improved method and apparatus which enables the continuous setting of such blind rivets in a manner which promotes efficient and effective riveting on a production line basis.
2. Description of the Prior Art
Typically, blind rivet type fasteners are characterized by a flanged eyelet or outer rivet section which is connected to a generally elongated mandrel having a somewhat enlarged head portion at one end thereof which engages the eyelet portion. Ordinarily, this mandrel projects through the eyelet portion and is usually adapted to cooperate with an appropriate type of chuck assembly therefor. The eyelet portion, on the other hand, is normally arranged to slidably interfit with formed and aligned apertures in workpieces of material which are to be suitably riveted together. Generally, to effectuate a riveting action for such kind of rivet, the protruding portion or shank of the mandrel is subjected to a tensile force which is sufficient in magnitude to effectively pull the mandrel relative to the eyelet portion. During this pulling procedure, the mandrel head deforms the eyelet to form a second flange which is spaced away from a first flange formed on the eyelet while a segment of the mandrel eventually separates from the remainder thereof, thereby leaving the workpieces in a locked or riveted condition. The foregoing types of blind rivet fasteners find a relatively wide variety of industrial uses and are often utilized, for example, to effectively rivet together workpieces made of sheet metal or the like.
In this particular riveting field, there are several known mechanisms which are capable of setting such of the aforedescribed forms of blind rivets. The more conventional category of such mechanisms is a hand-held operated rivet setting apparatus. These types of mechanisms may be normally characterized as including two levers or tong arms which are pivotably moved relative to each other, wherein one of such arms includes a conventional chuck assembly for holding the mandrel of the blind rivet. To effect a riveting operation, the levers are appropriately manually operated, with some degree of physical effort, so as to operate the chuck assembly to rupture the rivet mandrel, thereby setting the rivet in the material.
Although the foregoing described type of mechanism performs satisfactorily in a number of work applications, it suffers certain shortcomings, whenever it is contemplated that such riveting be accomplished on an assembly or production line basis. As can be readily appreciated, for each riveting operation there must be a corresponding manual operation of the levers with both hands. In addition, after each individual rivet setting operation is performed, the mechanism must be reloaded with another blind rivet. Quite obviously, such a riveting operation would be a somewhat slow procedure for production rivet work. Aside from the shortcomings previously mentioned which are associated with this category of riveting mechanism, others which also exist are that they are not as versatile and are somewhat awkward in situations wherein it is desired to rivet multiple layers of workpieces which are ganged together, especially if each of such workpieces are to assume a specific angular orientation with respect to each other. As can be readily appreciated, it would be extremely difficult to insure and maintain the proper alignment of such several workpieces since both hands would be required to operate the mechanism to set the rivet. Additionally, it is believed evident from the foregoing description that this particular manner of riveting is at times awkward, and, of course, not as fast as would be desirable. Furthermore, such riveting operation would be made even more cumbersome if, for example, the pieces to be riveted were relatively heavy for the operator to easily handle or relatively awkward to conveniently manually grip. Such shortcomings have a tendency to require that an operator expend significantly more time and energy in riveting blind rivets by hand. Consequently, of course, a relatively considerable amount of time, effort and costs are required to be expended whenever completing a sizeable number of riveting operations, such as would be the case on a production line basis.
Other similar kinds of blind rivet setting mechanisms may be pneumatically actuated. In this particular manner, it is somewhat less strenuous for an operator to actuate the rivet setting mechanism. However, such pneumatic operated rivet setting mechanisms nonetheless suffer from the previously described disadvantages, such as having to be reloaded with new blind rivets after every operation, as well as the various difficulties attendant with handling and accurately aligning several workpieces which may be required to be ganged together with specific angular orientations relative to each other, and which further may be heavy and/or cumbersome.
Another known approach to improve upon the aforedescribed difficulties typically encountered in setting blind rivets is generally described in U.S. Pat. No. 3,110,858. In this particular patent, an automatic rivet setting apparatus is disclosed as utilizing a motor driven rotor member which carries a plurality of chucks for selectively receiving blind rivets which are automatically fed to them for subsequent rivet setting operations. Despite that the foregoing provides a certain degree of improvement over the previously described prior art mechanisms, it nonetheless suffers from similar as well as additional disadvantages. In the above-referenced patent, the rotor member which carries the rivet chuck assemblies is incrementally advanced in a generally vertical plane such that the chuck assemblies carrying each of the individual rivets is moved downwardly and toward the operator's body during a normal rivet setting operation. For instance, with the foregoing apparatus, it is relatively difficult for an operator to effectively rivet together workpieces because such workpieces normally have to be held by two hands held in front of the operator. Such working conditions, for example, make it rather difficult for effectively riveting several pieces which are ganged into multiple layers. Another somewhat difficult rivet setting operation to perform with this type of apparatus would be to align and maintain alignment of multiple layers through the use of two hands such that each of the layers are situated in a predetermined orientation. In addition, such apparatus is relatively complicated in construction and has relatively many moving parts. Therefore, there is an increased likelihood that such apparatus will be subject to more breakdowns and repairs.
Besides the foregoing disadvantages, if the workpieces are relatively heavy, large or otherwise cumbersome to conveniently handle, the task of satisfactorily riveting such workpieces together would also be correspondingly relatively more difficult and time consuming.
Since, as previously observed, an operator working on such apparatus ordinarily stands immediately in front of the rotor, there might exist a likelihood that injury would occur should any portion of the operator's body or clothing inadvertently contact the moving rotor. For instance, the operator's leg might be struck by one of the chuck assemblies as the latter rotates downwardly, perhaps inflicting serious injury. From the foregoing description of this particular type of rivet setting apparatus, it is believed readily apparent that such apparatus is, as with the ones previously described, subject to several significant disadvantages; especially when considered from the standpoint of production work, wherein speed, ease of operation, and safety are important factors.
Consequently, heretofore known blind rivet setting mechanisms have in general failed to adequately enable the efficient and safe setting of blind type rivets, especially on a production line basis. Moreover, with such known forms of apparatus it is relatively difficult for a single operator to efficiently, accurately, and safely align several workpieces ganged together regardless of size, weight, or particular angular orientation in a convenient and reliable manner.